Christopher Ondaatje: Wealthy donors are moving towards Labour

As a result, a new limit of �20m was imposed in an attempt to avert excessive, US-style campaigns.

And with the election still expected on 3 May, both parties are now out and about with their begging bowls desperately looking for donors to foot their bills.

Unfortunately, their traditional sources of revenue have started to dry up.

The unions, who originally bankrolled Labour, have answered New Labour's decision to loosen its relationship with them by offering less cash than usual.

They were expected to contribute about �12m to the election campaign, but it is now feared that Tony Blair will be lucky to see �8m.

Controversial donors

Meanwhile, the Tories can no longer automatically rely on big business and wealthy individuals, domestic or foreign, to bail them out.

Both parties are attempting to whip up financial support from wherever it may be available. Individual membership donations are not going to be enough.

One of the problems the Tories have in attacking Labour over the funding issue, however, is their own previous record of secrecy and controversial donors such as Asil Nadir.

As a result, Labour clearly thinks it can turn the funding row into a positive story, with claims that people are lining up to finance its campaign for fear of letting the Tories back into power.

Party leaders are also quick to point out that they are being open, even when the rules do not yet require it, and that the Tories are still keeping their donors secret.

Coup by party

Lord Sainsbury's donation is no great surprise - apart from the amount. But the gift from Christopher Ondaatje, a disillusioned Tory, is being portrayed as a great coup by the party.

It is being claimed that the donations show how Labour is still trusted by business and is even seen as a better bet for government than the Tories.

And there is no doubt the Tories must be green with envy at the amounts being given by the sort of individuals they once relied upon.

There are suggestions that the party is struggling to get anything like the same level of funding from its supporters.

However many Labour backbenchers are still deeply concerned that the party is "in hock" to a small number of very rich individuals.

Backbench critics

No one is yet saying so openly, but the fear is that - with echoes of the Bernie Ecclestone affair - there may be strings attached.

Labour is dismissing this, insisting it gets money from all sorts of sources and will never allow donors to dictate policy.

Backbench critics are also worried that the names have only been revealed because the Economist magazine was about to "out" them anyway.

And, as with the Lord Hamlyn revelation, it looks like the party was originally seeking the big donations before its own rules on disclosure come into effect on 16 February.

All this is likely to contribute further to the debate about possible state funding of the political parties. But that will not come before the next election.

What is absolutely certain is that the whole issue of who is now bankrolling the two parties' election campaigns is going to be a significant factor in that campaign.